I often hear the Celtics referred to as "the C's". Obviously the C represents Celtics but what is the origin of this reference? I don't hear the Lakers referred to as "the L's" for example, so I am curious.

I often hear the Celtics referred to as "the C's". Obviously the C represents Celtics but what is the origin of this reference? I don't hear the Lakers referred to as "the L's" for example, so I am curious.